CPU Overclocking vs. Power Consumption. Page 15

Processor power consumption is closely connected with their clock frequency. That is why when overclockers increase their system performance they sacrifice energy efficiency. But how serious this problem actually is? We tested nice different processors from Athlon II, Core 2, Core i3, Core i7 and Phenom II families overclocked to different levels and are ready to give you an extensive answer to this question.

3D Games

Until this moment we have been talking about applications that load primarily the CPU, but not the graphics sub-system. Of course, graphics card was used to display images on the screen, but in this case it worked only in 2D mode, and ATI Radeon HD 5870 graphics accelerator that we had in our testbeds is extremely economical in this mode. It consumes no more than 25 W. The performance of our test systems in 3D is a completely different story, as not only the CPU but also the GPU contributes a lot to the total system power consumption score. In order to check how overclocking affects the power consumption of gaming systems we included a popular 3D shooter into our today’s test session.

Here average processor power consumption is significantly low that during rendering or video transcoding. However, the graphics card does consume much more power. This relocation of the power consumption focus allows us to conclude that relative effect from CPU overclocking on the resulting power consumption readings has become lower. Yes, overclocked gaming systems do need more power in games. But if we compared the obtained results with one another we will see that even when we raise the processor core voltage it in fact contributes no more than 20% into the total system power consumption under gaming load. Overall, average power consumption of overclocked systems (with one contemporary graphics accelerator inside) is about 200-250 W during active gameplay.

High CPU Utilization

Applications like 3D modeling or video transcoding and editing suites do load processors pretty heavily. However, there are even harder tasks for processors out there. For example, Linpack – a software library for solving linear algebraic equation systems. It was used to create LinX test utility, which we use to load processors to the utmost extent (in terms of power consumption).

Power consumption in this test does in fact turn out pretty high. For example, overclocked systems with the least energy-efficient quad-core Phenom II X4 965, Core i7-950 and Core i7-860 processors consume about 250-350 W of power. And these numbers are really high and they look even more impressive especially against the background of non-overclocked platforms with dual-core Core i3-540 and Core 2 Due E7600 processors that only require about 100 W.